As a word buff (OK, fine, word geek), I read books on subjects like "words that have been forgotten" and "words that only exist in one language" and, most recently, "surprising origins of common words."
Turns out, many of the words we use as put-downs of certain types of people were actually once slurs against certain groups of people— foreigners, women, the poor, and those of a minority faith or a specific ethnic group. "Nazi" is rapidly sliding down this slippery slope from "a particular group of murderous, fascist bigots engaged in government-enforced genocide" to "anyone strict with a rule I think should be flexible." Here are some words that have already made this slide:
The Greeks said that non-Greek speakers sounded like they were just saying so many nonsense syllables: "bar-bar-bar." The rest of us got back at them, sorta, with the Shakespearean saying "It's all Greek to me," which means, "It may as well be gibberish for all I can understand it."
To give someone less than what was promised. This word may be a slur against the Gypsy people, now more politely called the Roma, although that might also be a folk etymology. It's also possible it comes from a word for lowly kitchen workers, named after their tunics, called "gippos." (And isn't it interesting that they are called "Gypsies" because they were falsely thought to come from Egypt, when in fact they originate in India… while Native Americans were called "Indians" because they were falsely thought to come from India?)
Crossing an intersection from, say, the southeast to the northwest corner is called this because another word for "out-of-towner" or "yokel" is "jay." Those new to city life, not knowing traffic laws, would intuitively cross an intersection in the most direct manner instead of at right angles.
Now meaning someone who defaces property, perhaps by spraying graffiti on a building, this word comes from a case of sore loser-ship. The original Vandals were "a member of a Germanic people who overran Gaul (ancient France), Spain, and northern Africa in the fourth and fifth centuries CE, and in 455 sacked Rome." The Roman response? To use their name as an insult.
Obviously, a slur against the Welsh people. The word means "to renege on a debt." (Sometimes spelled "welch.")
This term, now meaning "American" (or "member of a rich baseball team"), has origins that are muddy at best. The best guess is that it was originally a slur against the Dutch by the English, who ran into each other in New Amsterdam and early New England. It either made fun of Dutch names… or their love of cheese. The term then broadened to include all New-Worlders, including the British colonists themselves, and the word was used to insult them by British loyalists once the Revolution got underway. The now-Americans embraced it instead.
Now replaced by the more polite "homeless person," the word originally mean "sponge, mooch," someone who was content to reap the benefit of others' work. Message? "You're poor because you're lazy."
In English feudal law, land owned by a serf with no heirs would "escheat," or revert to the lord of that region. It is not surprising that those survivors not considered legal heirs would feel "cheated."
Now mostly confined to "a kid who routinely skips school" it was first another word for someone who did not work. It was assumed that they simply didn't want to, not that they were unemployable due to circumstances beyond their control. (See "Bum," above.)
It now means "tasteless, offensive," but once just meant "common, not noble." The "Vulgate," for example, is the standard Catholic bible, in the then-common language of Latin.
This baseball team name embraces a slur against certain New Yorkers. Because Brooklynites had to run between streetcars to cross the street, Manhattanites dubbed them "trolley-dodgers." A far cry from today, when public transportation is hailed as solution for everything from traffic jams to pollution.
As in "dude ranch." The laid-back ranchers at these ranches liked to mock stuffy, dirt-averse city folk who came to play cowboy as "dudes," which meant "dandies."
Now a word meaning "someone yet unconverted to a given faith," it comes from the word "heath," and referred to someone living outside the city.
Today, this means "ferocious." But it comes from a word simply meaning "forest related" or "forest dwelling."
The root "hyster"— as in "hysterectomy"— means "uterus." When a woman was accused of acting with heightened emotions, regardless of the reason (which may have been legitimate!), this was attributed to uterus-related problems. (Relatedly, "lunatic" comes from the same word as "lunar," meaning "moon-related"; the word "moon" gives us both "month" and "menstruate.")
Now someone puritanical and anti-fun, it originally meant simply a "good woman," a prudent, decent one… perhaps the female equivalent of a "mensch."
A crude and aggressive person. But first, an animal. As if all animals lacked grace and tenderness— didn't these people own horses and dogs?
This word means "evil, malicious"… but originally just meant "left-handed." Meanwhile, "dexterous," or "agile, skilled," meant "right-handed."
Other, older words that began in as slurs against a specific group include: "Scalawag," "Vagabond," "Blackguard," "Cad," "Knave," " Lout," "Rascal" "Rapscallion," "Rube," "Riffraff," "Cretin," and "Dunce."
I have nothing against denouncing bad behavior. But reprimands cross a line when they denounce someone for who they are, not what they did. As these words show how today's offensive, lawsuit-worthy, career-ending slurs can become tomorrow's generic insults. Bigotry against foreigners, the poor, and other minorities deeply impacts our speech and the way we think and act toward others we consider inferior.